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FILE - In this Dec. 17, 2012 file photo, stuffed animals and a sign calling for prayer sit at the base of a tree near the Newtown VIllage Cemetery in Newtown, Conn., after 26 people were shot to death at Sandy Hook Elementary School. Newtown officials and families of those killed have given away 63,790 stuffed animals and thousands of other gifts that poured into the town in the weeks following the massacre. The final boxes of toys and school supplies were shipped out of the warehouse on March 29, 2013. (AP Photo/Charles Krupa, File)

The Connecticut school system unwittingly enabled Adam Lanza's mother in her preference to "accommodate and appease" him as he became more withdrawn socially, according to a state report issued Friday on the man who carried out the 2012 massacre at Sandy Hook Elementary School.

The Office of the Child Advocate identified missed opportunities to provide more appropriate treatment for Lanza, whose social isolation and obsession with mass killings have been detailed by police reports that found the motive for the shootings may never be known.

The advocate's office investigates all child deaths in the state for lessons on prevention. The authors of the Newtown report said it aims to reinforce the importance of effective mental health treatment and communication among professionals charged with the care for children.

The report, which refers to Lanza only as "AL," noted that recommendations by specialists for extensive special education support and expert consultations largely went unheeded.

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"Records indicate that the school system cared about AL's success but also unwittingly enabled Mrs. Lanza's preference to accommodate and appease AL through the educational plan's lack of attention to social-emotional support, failure to provide related services, and agreement to AL's plan of independent study and early graduation at age 17," the authors wrote.

The authors of the 114-page report said they could not say whether more effective treatment could have prevented the tragedy.

"This report raises, but cannot definitively answer, the question as to whether better access to effective mental health and educational services would have prevented the tragic events at Sandy Hook," they wrote.

Lanza killed his mother, Nancy Lanza, then shot his way into the Newtown school on Dec. 14, 2012, and gunned down 20 children and six educators before committing suicide.

The police investigation into the massacre concluded more than a year ago with prosecutors saying in a summary report that a motive might never be known. It said Lanza was afflicted with mental health problems, but despite his dark interests, he did not display aggressive or threatening tendencies.

Documents released by police in December 2013 included descriptions of sporadic treatment for his mental health troubles. At one point, experts at the Yale Child Studies Center prescribed antidepressant/anti-anxiety medication, but his mother, Nancy Lanza, discontinued the treatment after her son was unable to raise his arm after taking the medicine and never scheduled follow-up visits, police reports said.

A Connecticut judge last year ordered Newtown school officials to give Lanza's records the Office of Child Advocate for its investigation. The governor's Sandy Hook Advisory Commission has been waiting for the office's report before releasing its recommendations on what the state can do to prevent and respond to future mass killings.

Child Advocate Sarah H. Eagan already has met with the families of the victims and Newtown school officials to discuss the findings.